We propose a Program of Projects to advance the applied science of evaluating health-related quality of life (HRQOL) in older U.S. adults. We simultaneously use four widely-used generic HRQOL instruments, the SF-36v2, EuroQol EQ-5D, Quality of Well-being scale (QWB-SA), and Health Utilities Index (HUI2/3). Additionally we use the HALex from the National Center for Health Statistics. Project 1 uses a telephone survey to interview a cross-sectional sample of 2800 non-institutionalized adult U.S. residents aged 35-89. Persons aged 65 and older will be over-sampled to provide higher precision in older ages. African Americans are over-sampled for the first national survey of substantial size (n=1000) of this important sub-population. Project 1 data will be used to construct gender- and age-specific national reference averages for HRQOL among older adults on all measures. Project 2 will use all four measures to follow treatment and 6 month recovery of patients with three age-related diseases stressing different aspects of HRQOL newly referred congestive heart failure, hip replacement for osteoarthritis, and cataract extraction. This project will establish characteristics of the measures for longitudinal follow-up of patients with self-administered questionnaires. Project 3 examines how duration of a health condition affects HRQOL assessments and how this affects interpretation of HRQOL scores from standardized indexes. This is particularly important in the elderly as medical care increasingly prolongs life with chronic conditions. Project 4 determines survey mode effects (telephone versus self-administration) for all instruments as well as English versus Spanish language administration for persons who are usually Spanish speakers. The Program will enhance health researchers' ability to measure, follow, and interpret HRQOL in adults and to assess health disparities.